36. What are minimal pairs?
When two different phonetic forms are identical in every way except for one sound segment which occurs in the same place in the string, the two forms (i. e., word) are supposed to form a “minimal pair”, e.g., “pill” and “bill”, “pill” and “till”, “till” and “dill”, “till” and “kill”, etc. All these words together constitute a minimal set. They are identical in form except for the initial consonants. There are many minimal pairs in English, which makes it relatively easy to know what are English phonemes. It is of great importance to find the minimal pairs when a phonologist is dealing with the sound system of an unknown language.
37. What is free variation?
If two sounds occurring in the same environment do not contrast; namely, if the substitution of one for the other does not generate a new word form but merely a different pronunciation of the same word, the two sounds then are said to be in “free variation”. The plosives, for example, may not be exploded when they occur before another plosive or a nasal (e. g., act, apt, good morning). The minute distinctions may, if necessary, be transcribed in diacritics. These unexploded and exploded plosives are in free variation. Sounds in free variation should be assigned to the same phoneme.
38. What is complementary distribution?
When two sounds never occur in the same environment, they are in “complementary distribution”. For example, the aspirated English plosives never occur after [s], and the unsaturated ones never occur initially. Sounds in complementary distribution may be assigned to the same phoneme. The allophones of [l], for example, are also in complementary distribution. The clear [l] occurs only before a vowel, the voiceless equivalent of [l] occurs only after a voiceless consonant, such as in the words “please”, “butler”, “clear”, etc., and the dark [l] occurs only after a vowel or as a syllabic sound after a consonant, such as in the words “feel”, “help”, “middle”, etc.
39. What is the assimilation rule? What is the deletion rule?
The “assimilation rule” assimilates one segment to another by “copying” a feature of a sequential phoneme, thus making the two phones more similar. This rule accounts for the raring pronunciation of the nasal [n] that occurs within a word. The rule is that within a word the nasal consonant[n] assumes the same place of articulation as the following consonant. The negative prefix “in-“ serves as a good example. It may be pronounced as [in], or [im] when occurring in different phonetic contexts: e. g., indiscrete-[    ] (alveolar) inconceivable-[    ](velar) input-[‘imput] (bilabial)
The “deletion rule” tells us when a sound is to be deleted although is orthographically represented. While the letter “g” is mute in “sign”, “design” and “paradigm”, it is pronounced in their corresponding derivatives: “signature”, “designation” and “paradigmatic”. The rule then can be stated as: delete a [g] when it occurs before a final nasal consonant. This accounts for some of the seeming irregularities of the English spelling.
40. What is suprasegmental phonology? What are suprasegmental features?
“Suprasegmental phonology” refers to the study of phonological properties of linguistic units larger than the segment called phoneme, such as syllable, length and pitch, stress, intonation.
41.  What is morphology?
“Morphology” is the branch of grammar that studies the internal structure of words, and the rules by which words are formed. It is generally divided into two fields: inflectional morphology and lexical/derivational morphology.
42. What is inflection/inflexion?
“Inflection” is the manifestation of grammatical relationships through the addition of inflectional affixes, such as number, person, finiteness, aspect, and case, which does not change the grammatical class of the items to which they are attached.
43. What is a morpheme? What is an allomorph?
The “morpheme” is the smallest unit in terms of relationship between expression and content, a unit which cannot be divided without destroying or drastically altering the meaning, whether it is lexical or grammatical. The word “boxes”, for example, has two morphemes: “box” and “-es”, neither of which permits further division or analysis if we don’t wish to sacrifice meaning. Therefore a morpheme is considered the minimal unit of meaning. Allomorphs, like allophones vs. phones, are the alternate shapes (and thus phonetic forms) of the same morphemes. Some morphemes, though, have no more than one invariable form in all contexts, such as “dog”, “cat”, etc. The variants of the plurality “-s” make the allomorphs thereof in the following examples: map-maps, mouse-mice, sheep-sheep etc.
44. What is a free morpheme? What is a bound morpheme?
A “free morpheme” is a morpheme that constitutes a word by itself, such as ‘bed”, “tree”, etc. A “bound morpheme” is one that appears with at least another morpheme, such as “-s” in “beds”, “-al” in “national” and so on. All monomorphemic words are free morphemes. Those polymorphemic words are either compounds (combination of two or more free morphemes) or derivatives (word derived from free morphemes).
45. What is a root ? What is a stem? What is an affix?
A “root” is the base form of a word that cannot be further analyzed without total loss of identity. In other words, a “root” is that part of the word left when all the affixes are removed. “Internationalism” is a four-morpheme derivative which keeps its free morpheme “nation” as its root when “ inter-”, “-al” and “-ism” are taken away.
A “stem” is any morpheme or combination of morphemes to which an affix can be added. It may be the same as, and in other cases, different from, a root. For example, in the word “friends”, “friend” is both the root and the stem, but in the word “friendships”, “friendships” is its stem, “friend” is its root. Some words (i. e., compounds ) have more than one root ,e. g., “mailman” , “girlfriend” ,ect. An “affix” is the collective term for the type of formative that can be used, only when added to another morpheme(the root or stem). Affixes are limited in number in a language, and are generally classified into three subtypes: prefix, suffix and infix, e. g. , “mini-”, “un-”, ect.(prefix); “-ise”, “-tion”, ect.(suffix).
46. What are open classes? What are closed classes?
In English, nouns, verbs, adjectives, and adverbs make up the largest part of the vocabulary. They are “open-class words”, since we can regularly add new lexical entries to these classes. The other syntactic categories are, for the most part, closed classes, or closed-class words. The number of them is hardly alterable, if they are changeable at all.
47.  What is lexicon? What is word? What is lexeme? What is vocabulary? Lexicon? Word? Lexeme? Vocabulary?
“Lexicon”, in its most general sense, is synonymous with vocabulary. In its technical sense, however, lexicon deals with the analysis and creation of words, idioms and collocations. “Word” is a unit of expression which has universal intuitive recognition by native-speakers, whether it is expressed in spoken or written form. This definition is perhaps a little vague as there are different criteria with regard to its identification and definition. It seems that it is hard, even impossible, to define “word” linguistically. Nonetheless it is universally agreed that the following three senses are involved in the definition of “word”, none of which, though, is expected to cope with all the situations: (1) a physically definable unit, e.g. [it iz ‘w   ] (phonological), “It is wonder” (orthographic); (2) the common factor underlying a set of forms (see what is the common factor of “checks”, “checked”, “checking ”, etc.); (3) a grammatical unit (look at (1) again; every word plays a grammatical part in the sentence). According to Leonard Bloomfield, a word is a minimum free form (compare: a sentence is a maximum free form, according to Bloomfield). There are other factors that may help us identify words: (1) stability (no great change of orthographic features); (2) relative uninterruptibility (we can hardly insert anything between two parts of a word or between the letters). To make the category clearer we can subclassify words into a few types: (1) variable and invariable words; (2) grammatical and lexical words (e. g. to, in, etc., and table, chair, etc. By “lexical words” we mean the words that carry a semantic content, e.g., nouns, verbs, adjectives and many adverbs; (3) closed-class and open-class words. In order to reduce the ambiguity of the term “word”, the term “lexeme” is postulated as the abstract unit which refers to the smallest unit in the meaning system of a language that can be distinguished from other smaller units. A lexeme can occur in many different forms in actual spoken or written texts. For example, “write” is the lexeme of the following words: “write”, “write”, “wrote”, “writing”, and “written.” “Vocabulary” usually refers to all words or lexical items a person has acquired about technical or/and untechnical things. So we encourage our students to enlarge their vocabulary. “vocabulary” is also used to mean word list or glossary.